Enlarged Image for Wolff-Parkinson-White Syndrome

In this view of the heart, the arrows represent electrical signals beginning at the sinus node, activating both atria and then passing through the atrioventricular node on their way back to the ventricles. The panel below the heart is a typical electrocardiogram (ECG or EKG) recording of a normal heart rhythm.

Wolff-Parkinson-White syndrome — In this view of the heart, the arrows represent the path of electrical activity when AVRT is present. The accessory pathway is an abnormal "bridge" of tissue that allows the heart's electrical impulse to travel in a circular pattern from the ventricles to the atria. The panels below the heart are typical electrocardiogram recordings from a heart with manifest WPW with accessory pathway (left) and a heart with tachycardia (right).